Avedon's instructions to his printer: the red marks indicate areas to be dodged and burned.
Some photographers despair at the notion of altering their photographs in post-processing, believing that doing so is a distortion of truth. What this fails to acknowledge is the fact that alteration of the raw image is needed to render something that approximates what we see with the naked eye.
Post-processing of digital photographs utilizes software such as Photoshop, Lightroom or Aperture to adjust the original image in terms of colour, tonal range, brightness and so forth. Recognition of Photoshop’s ability to significantly alter portions of the image is so widespread that the noun has become a verb (see, for example, “Has that photo been photoshopped?“). And for those who think such alterations are purely the stuff of digital capture, they need only consider the instructions of the photographic masters of film handed to their printers (see the image to the right, borrowed from Chase Jarvis’ blog. And while you’re at it, take a look at the documentary entitled War Photographer, which chronicles the incredible work of James Natchwey. This film includes a rather entertaining segment in which Natchwey sends his darkroom assistant back and forth multiple times in an attempt to bring out further detail in the sky of one image.)
The reason for all of this has to do with the way our eyes and brains interpret a scene, versus the way a recording medium, be it film or digital sensor, records that same scene. I use the word “interpret” deliberately, because much of what we see is a reinterpretation of the raw signals our eyes send to the brain. This is evidenced in part by experiments in which human subjects were asked to wear coloured contact lenses for extended periods. Within several hours the subjects became unaware of the colour cast produced by the lenses. (You likely notice a similar effect after wearing sunglasses for extended periods.) This adaptation is all part of our evolutionary heritage, something static recording media such as film and digital sensors lack. So, we have to modify the raw image in order for it to better approximate what we perceive with our “mind’s eye”, so to speak.
Visual Acuity versus luminance (Riggs L. A., Visual acuity. Chapter 11. In: Graham, C. H. (ed), Vision and Visual Perception. New York: John Wiley and Sons, Inc., 1965)
Our eye-brain complex is also highly nonlinear in its sensitivity to light. Under conditions of low illumination, the eye-brain is still an able to extract detail in the scene as our rods work overtime. Likewise, at the upper extremes of illumination we are still able to perceive details in the highlights of a scene. The overall range of contrast detection for the human eye is reported to be approximately 10,000:1 (equivalent to about 13 f-stops). Unpublished tests of Nikon’s D3 (my camera) suggest a dynamic range for this camera of around 3326:1 (i.e. 11.7 f-stops) – not as good as my good eye. Perhaps even more important, digital sensors record light in a linear fashion, unlike the eye (or film for that matter) so that if one were to take the captured image at face value without correcting for tonal limitations and linear behaviour, it would appear dark and flat.
For these (and various other) reasons, photographs must be massaged to be properly interpreted. All digital cameras do some of this for us internally when recording the image by adjusting colour balance and tonal range (for reasons mentioned earlier), as well as to introduce sharpening to compensate for demosaicing effects. The result of these initial adjustments is what you see in the image rendered on the back of your camera after photographing a subject. By shooting in RAW format, however, you are free to over-ride all of these initial adjustments using what we refer to as post-processing software, such as Lightroom or Aperture. The question then becomes: do you trust some engineer from your camera manufacturer to interpret your images, or would you rather do it yourself by shooting in RAW and then post-processing them?
As a colonialist, consumerist manipulator who has inhibited true globalization, disabling the discourse of reality as perceived by ‘other’ cultures through hegemonic power plays I prefer to take control of the post-processing in my work, as do all imperialist photographers with whom I hang out. Part of this alteration is to correct inaccuracies in the raw capture, as discussed above. But more often it further involves a reinterpretation and subsequent alteration of the image to better communicate the message behind the medium.
Of course, image manipulation has its pros and con artists – blog-fodder for another day…
